1. Field of the Invention
This invention relates to a method for immunologically analyzing trace components, more particularly, to a method for photochemically analyzing in a quantitative manner trace components utilizing immune reaction.
2. Description of the Prior Art
Radioimmunoassay (hereafter merely "RIA") is a method for the assey of trace components utilizing a specific antigen-antibody reaction. The basic principles of RIA are as follows. The reaction of a substance labelled or marked (hereafter these terms are used interchangeably) with a radioactive isotope (RI) in a given amount and a substance having a specific binding affinity thereto in a given amount results in a coupled product of both of these components, while a part of the labelled substance remains in an unbound or unreacted free state. The reaction proceeds based on the laws of mass action in general and therefore, when an unlabelled substance is added to the reaction system, binding with a limited amount of binding protein is decreased and a certain relationship (calibration curve) is established therebetween. As a result, an amount of an unknown substance can be determined from the calibration curve if the bound substance and the labelled substance in the free state are separated and either one or both are measured with respect to RI amount.
Due to the high sensitivity and the simplicity of RIA, RIA is particularly applicable to the measurement and inspection of trace amounts of proteins in blood and hormones. Details thereon are given in, e.g., Kumahara and Shizume, New Radioimmunoassay, pages 3 to 10, 1977, published by Asakura Publishing Co., Ltd., KISO SEIKAGAKU JIKKENHO (Basic Biochemical Experiment) (6) and SEIKAGAKUTEKI SOKUTEI (Biochemical Assay), 1967, published by Maruzen Co., Ltd., Tokyo.
However, RIA is subject to several disadvantages due to the use of RI markers (.sup.125 I, .sup.131 I, etc.) as good markers are markers having high specific radioactivity which maintain immune activity and are radioactively of high purity. For these reasons, RIA involves the danger of radiation exposure and requires the management of expensive and unstable markers which cannot be used for long periods of time. In addition, special installations, equipment and personnel qualified to deal with radiation are required. Finally, after RIA, pollution problems are encountered due to the necessity to dispose of radioactive waste.